Shooting game machine and method for performing it

ABSTRACT

The present invention discloses an infrared detection type shooting game machine and method, which changes the degree of difficulty and environment of a game depending upon a distance measured using a plurality of references arranged at irregular intervals, thus providing realistic and interesting games. The shooting game method includes (a) displaying images, including a mark, by a display means and displaying a plurality of references that are bases for detection of coordinates; (b) detecting a partial image of a certain region of a point indicated through . an indication means manipulated by a player; (c) receiving the detected partial image, detecting coordinates of the references, and setting coordinates of the references to the detected coordinates of the references; (d) detecting indicated coordinates of the point indicated by the player based upon the coordinates of the references; (e) measuring a distance D between the display means and the indication means based upon previously stored intervals between the plurality stored intervals between the plurality of references and distances between the coordinates of the references; and (f) setting reference distances D 0  to some of distances D between the display means and the indication means falling within a certain range, and changing a degree of difficulty and situations of the game depending upon whether the reference distances are fulfilled.

TECHNICAL FIELD

The present invention relates generally to a shooting game machine, andmore particularly to an infrared detection type shooting game machineand method, which changes the degree of difficulty and environment of agame depending upon a distance measured using a plurality of referencesarranged at irregular intervals, thus providing realistic andinteresting games.

BACKGROUND ART

The present invention is the improvement of Korean Pat. Appl. No.10-2002-43913 filed on Jul. 25, 2002 and entitled adjustment of thedegree of difficulty and situations in a game. The contents of thispatent application, closely related to the present invention, areincorporated herein.

Referring to FIG. 1 illustrating the perspective view of a prior artshooting game machine, the prior art shooting game maclijne includes agame machine box 1, a screen 1 a, an image generator 2 positioned in thegame machine box 1, a translucent reflecting mirror 3 for displaying animage generated from the image generator 2 on the screen 1 a, aninfrared ray generating device 4 for generating references 7 that arethe bases for the calculation of coordinates, a control means 5 forcontrolling the entire shooting game machine, and a coordinate detectingmeans 6 for detecting coordinates indicated by a player based on thereferences by the infrared ray generating device 4.

Further, the shooting game machine further includes a model gun 10 forpointing at a mark on the image displayed on the screen 1 a. The modelgun 10 includes a barrel 10 a, a trigger 11, a vibration-proof member 12such as rubber, a Charge Coupled Device (CCD) camera 13, a lens 14 andan infrared ray pass filter 15. An image detected through the CCD camera13 is transmitted to the coordinate detecting means 6 via acommunications line 16 connected to the model gun 10. A CCD of the CCDcamera 13 is generally rectangularly shaped, and the CCD is used withthe side thereof having a greater number of pixels arranged along ahorizontal direction.

A display means for displaying the image of a game in the shooting gamemachine constructed as described above includes the screen 1 a, theimage generator 2 and the translucent reflecting mirror 3. The imageinformation of the game, including a mark, transmitted from the controlmeans 5 is converted into the light of a visible light range by theimage generator 2, reflected by the translucent mirror 3, and finallyirradiated to the screen 1 a, thus being observed by the player. In thiscase, light emitted from the infrared light generator 4 is reflected bythe translucent reflecting mirror 3 and irradiated to the screen 1 a,thereby indicating the references 7 that are the bases for the detectionof coordinates.

The player points to the screen 1 a with the model gun in this hand. Inthis case, the image and the references 7 displayed on the screen 1 areach the infrared ray pass filter. At this time, the light of a visibleray range cannot pass through the infrared ray pass filter 15, while thereferences 7, that is, the light of an infrared ray range, passesthrough the infrared ray pass filter 15.

The references 7 having passed through the infrared ray pass filter 15form images on the CCD camera 13 through the lens 14, the references 7having formed images on the CCD camera 13 are converted into an imagecomposed of electric signals, and the image of electric signals aretransmitted to the coordinate detecting means 6. At this time, when theplayer pulls the trigger 11, the coordinate detecting means calculatesthe coordinates of the references and obtains indicated coordinates,that is, indicated coordinates on the screen 1 a indicated by theplayer, based on the coordinates of the references.

The indicated coordinates obtained as described above are transmitted tothe control means 5, and the control means 5 determines whether a markis hit by comparing the coordinates at the moment the player pulled thetrigger 11 with the indicated coordinates.

However, the prior art shooting game machine has disadvantages in thatit is impossible to accurately calculate a position, since one, two ormore references generated by the infrared ray generating device 4 aredistributed around the image without a specified rule and the indicatedcoordinates of the player are detected on the condition that it isassumed that the model gun 10 is not rotated.

That is, as shown in FIG. 4 a, in the prior art shooting game machine,two references {the coordinates of the references on the CCD camera 13are p₁=(p_(1X), p_(1Y)), p₂=(p_(2X), p_(2Y)) (it is assumed that theorigin of the coordinates of the CCD camera is the upper left corner)and the coordinates of the center of the screen 1 a on the screen 1 aare previously stored (X₀, Y₀)} generally arranged to be symmetrical tothe center of the screen 1 a, and the indicated coordinates are detectedonly when all the references are detected by the CCD camera 13.

The coordinate detecting means 6 calculates the coordinates {p₀=(p_(0X),p_(0Y))} of the centers (the centers of the references become the centerof the screen 1 a because the references are arranged to be symmetricalto the center of the screen 1 a) of the references on the CCD camera 13by the method of calculating the coordinates {p₁=(p_(1X), p_(1Y)),p₂=(p_(2X), p_(2Y))} of the references on the CCD camera 13 andobtaining the center of gravity. Since the distance D between thereferences on the CCD camera 13 is obtained by d=√{square root over((p_(2X)−p_(1X))²+(p_(2Y)−p_(1Y))²)}, the indicated coordinates areobtained by$X = {{X_{0} + {\left( {C_{X} - p_{0X}} \right)\frac{L}{d}\quad{and}\quad Y}} = {Y_{0} + {\left( {C_{Y} - p_{0Y}} \right)\frac{L}{d}}}}$when the coordinates of the center of the CCD camera 13 on the CCDcamera 13 are C=(C_(X), C_(Y)) and the distance between the referenceson the screen 1 a is L.

Accordingly, the prior art shooting game machine cannot obtain theaccurate indicated coordinates when the player is positioned very closeto the screen 1 a or far from the screen 1 a (all the references are notdetected by the CCD camera 13), and the prior art shooting game machinecannot obtain the accurate indicated coordinates when the rotation ofthe model gun 10 is taken into consideration as in the present inventionbecause the prior art shooting game machine employs a method ofcalculating the indicated coordinates without talking the rotation ofthe model gun 10 into consideration.

Further, since the prior art shooting game machine uses all thedisplayed references to detect the indicated coordinates 8 indicated bythe player and detects the indicated coordinates 8 in the abovedescribed manner, the prior art shooting game machine is disadvantageousin that the indicated coordinates 8 cannot be detected if part of thereferences are not detected due to the partial failure of the infraredray generating device 4.

Further, since the prior art shooting game machine can detect theindicated coordinates only when the prior art shooting game machinedetects all the used references, the prior art shooting game machine isdisadvantageous in that a range, which can be detected by the CCD cameraof the same size, is very small.

Further, in the prior art shooting game machine, the game is played onlyin such a way that the player passively acts in response to the contentsof the game provided by the control means 5. Additionally, the prior artshooting game machine is disadvantageous in that the prior art shootinggame machine cannot provide a realistic game because the prior artshooting game machine cannot reflect the detected rotation of the modelgun 10 and a detected variation in the distance between the model gun 10and the screen 1 a.

The distance between the model gun 10 and the screen 1 a may be changeddepending upon the player. The player in a good physical condition mayreduce the distance and play the game at a position close to the screen1 a. Since the position close to the screen 1 a can improve shootingaccuracy, equal games cannot be played. All players would desire to playgames at positions close to the screen 1 a.

Further, since the CCD camera 13 used in the prior shooting game machineis not fixed and can be freely moved by the player, an image can bedetected with the same CCD. The prior shooting game machine does notutilize resolution by detecting the indicated coordinates based upon theabove-described limited distribution of the references.

The index used to detect images in a shooting game machine is theresolution, and the resolution of the CCD of the CCD camera directlyaffects the image detection resolution. The method of increasing theresolution of the CCD is the easiest method to increase the imagedetection resolution. The method of increasing the resolution of the CCDhas limitations in cost and technology because the costs of the CCD areincreased and the amounts of data to transmit and process are increasedand a high-speed transmission method and a high-performance processingapparatus are required.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior art, and an object of the presentinvention is to provide a shooting game machine and method that canimprove an interest in an game by changing a game environment dependingupon the distance between a model gun and a screen.

Another object of the present invention is to provide a game shootingmachine and method that changes the progress of a game by changing theimages of a game and adjusting the degree of difficulty of a game, basedupon indicated coordinate detected by a player, rotation of a model gunor distance between a model gun and a screen.

Another object of the present invention is to provide a game shootingmachine and method, which sets a reference distance between a model gunand a screen, and makes a game difficult if an actual distance isgreater- than the reference distance and grants a benefit to the playerif the actual distance is shorter than the reference distance.

Another object of the present invention is to provide a game shootingmachine and method, in which indicated coordinates can be calculatedusing part of references by arranging a plurality of referencesaccording to a certain rule, so that indicated coordinates can not onlybe calculated in a wide range using a CCD camera of the same resolutionbut indicated coordinates can be also calculated in the same range usinga CCD camera of a low resolution.

Another object of the present invention is to provide a game shootingmachine and method, which sets a reference distance between a model gunand a screen, and increases the degree of difficulty by a reduction inthe size of a mark, the imposition of penalty, an increase in thedirectional angle of a bullet, etc. if the actual distance is greaterthan the reference distance and gives a benefit to the player byincreasing the size of a mark, providing an advantage, etc. if theactual distance is shorter than the reference distance.

In order to accomplish the above object, the present invention- providesa shooting game machine, including display means for displaying images,including a mark; reference displaying means for displaying a pluralityof references that are arranged inside or around the display means atirregular intervals and are bases for detection of coordinates;indication means for pointing at a point on the display mean, which isindicatedby a player; image detecting means mounted on the indicationmeans to detect an image of a region indicated by the indication means;reference coordinate detecting means for receiving the detected imageand detecting coordinates of the references; indicated coordinatedetecting means for detecting indicated coordinates indicated by theindication means based upon the detected coordinates of the references;arid control means for adjusting a degree of difficulty based upon adistance between the display means and the indication means, receivingthe detected indicated coordinates and controlling the entire shootinggame macline.

Preferably, the irregular intervals between the plurality of referencesmy be determined depending upon conditions of the shooting game machine,such as a resolution of the display means, a resolution, a visible rangeand a rotation limit of the image detecting means, and the distancebetween the display means and the indication means.

Preferably, the reference coordinate detecting means may detect actualinformation of the detected references based upon ratios of distancesbetween the detected references if the image detecting means detectspart of the references.

Preferably, the indicated coordinate detecting means may detectindicated coordinates based upon two of part of the references detectedby the image detecting means.

Preferably, the shooting game machine may further include rotationdetecting means for detecting rotation of the indication means basedupon the plurality of references.

Preferably, the control means controls the images displayed on thedisplay means based upon a variation of the indicated coordinatesdetected by the indicated coordinate detecting means or the rotationdetected by the rotation detecting means.

Preferably, the shooting game machine may further include a distancemeasuring means for detecting the distance between the display means andthe indication means based upon previously stored intervals between thereferences on the display means. and intervals between the references onthe image detecting means, which are detected by the image detectingmeans.

Preferably, the control means may control the images displayed on thedisplay means based upon a variation of the indicated coordinatesdetected by the indicated coordinate detecting means or the distancebetween the display means and the indication means detected by thedistance detecting means.

Preferably, the control means may control the images displayed on thedisplay means based upon a variation of the coordinates detected by theindicated coordinate detecting means.

Preferably, indication means includes an image generator, a translucentreflecting mirror and a screen displaying an image reflected by thetranslucent reflecting milTor. The reference display means is positionedbehind the translucent mirror.

Preferably, the indication means may be a model of one of a gun, atennis racket, a baseball bat, a baton, a rod or a sword.

In order to accomplish the above object, the present invention providesa shooting game method, including the steps of (a) displaying images,including a mark, by a display means and displaying a plurality ofreferences that are bases for detection of coordinates; (b) detecting apartial image of a certain region of a point indicated through anindication means manipulated by a player; (c) receiving the detectedpartial image, detecting coordinates of the references, and settingcoordinates of the references to the detected coordinates of thereferences; (d) detecting indicated coordinates of the point indicatedby the player based upon the coordinates of the references; (e)measuring a distance D between the display means and the indicationmeans based upon previously stored intervals between the plurality ofreferences and distances between the coordinates of the references; and(f) setting reference distances D₀ to some of distances D between thedisplay means and the indication means falling within a certain range,and changing a degree of difficulty and situations of the game dependingupon whether the reference distances are fulfilled.

Preferably, the distance D between the display means and the indicationmeans may be calculated by the following equation D≈f(L/d) where fdenotes a focal length of a lens, L denotes a distance between thereferences obtained by previously stored coordinates of the references,and d denotes the intervals between the references on a CCD camera;wherein the indication means is equipped at the front end thereof withthe lens and at the rear end thereof with the CCD camera.

Preferably, a directional angle δ₀ of the indicating means may beincreased if the distance D is shorter than the reference distance D₀,while the directional angle δ₀ of the indicating means may be reduced ifthe distance D is greater than the reference distance D₀.

Preferably, a size of the mark may be reduced if the distance D isshorter than the reference distance D₀, while the size of the mark maybe increased if the distance D is greater than the reference distanceD₀.

Preferably, a penalty may be granted to the player if the distance D isshorter than the reference distance D₀, while an advantage may begranted to the player if the distance D is greater than the referencedistance D₀.

Preferably, the penalty may be granted to the player by a combination ofa reduction in a moving speed of the player in the game, a limitation ina height of jumps and a reduction in game time.

Preferably, situations of the game may be set to be disadvantageous tothe player if the distance D is shorter than the reference distance D₀,while the situations of the game may be set to be advantageous to theplayer if the distance D is greater than the reference distance D₀.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a prior art shooting game machine;

FIG. 2 is a perspective view of a shooting game machine in accordancewith the present invention;

FIG. 3 a is a schematic diagram in which a prior art model gun points ata screen, and FIG. 3 b is a schematic diagram in which a model gunpoints at a screen in accordance with an embodiment of the presentinvention;

FIG. 4 a is a diagram illustrating a prior art method of calculatingcoordinates, and FIG. 4 b is a diagram illustrating a method ofcalculating coordinates in accordance with an embodiment of the presentinvention;

FIG. 5 a is a diagram illustrating a prior art method of calculatingcoordinates when part of lamps fail, and FIG. 4 b is a diagramillustrating a method of calculating coordinates when part of lamps failin accordance with an embodiment of the present invention;

FIG. 6 is a flowchart of an entire system according to the embodiment ofthe present invention;

FIG. 7 is a flowchart of a coordinate calculation algorithm according toan embodiment of the present invention;

FIG. 8 a is a diagram showing the method of using the CCD cameraaccording to the prior art, and FIG. 8 b is a diagram showing the methodof using the CCD camera according to an embodiment of the presentinvention;

FIG. 9 is a diagram showing the state in which a screen and anindicating means are spaced apart from each other;

FIG. 10 is a flowchart showing an example of a method of changing thedegree of difficulty and situations of a game depending upon thedistance between the screen and the indication means;

FIGS. 11 a to 11 e are flowcharts showing various examples in which thedegree of difficulty and situations of a game are changed;

FIG. 12 is a diagram showing the state in which a bullet deviates when atrigger is pulled; and

FIGS. 13 a and 13 b are diagrams showing an example in which the size ofa picture displayed on a screen is reduced. <Description of referencenumerals of principal elements in drawings> 1: game machine box 1a:screen 2: image generator  3: translucent reflecting mirror 4: infraredray generating device  5: control means 6: coordinate detecting means 7: references 8: indicated coordinates 10: model gun 11:  trigger 12:vibration-proof member 13:  CCD camera 14: lens 15:  infrared ray passfilter 16: communications line

BEST MODE FOR CARRYING OUT THE INVENTION

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings.

FIG. 2 is a perspective view of a shooting game machine according to thepresent invention.

A game machine box 1 contains elements constituting a game machineexcept for a model gun. A screen 1 a is the device that displays aplurality of references that are the bases for the detection of contentimages, including a mark, and indicated coordinates. An image generator2 is the device that generates images, including the contents of a gameand a mark. A brown tub or projector is used for the image generator 2.

A display means for indicating a mark is constructed to include thescreen 1 a, the image generator 2 and a translucent mirror 3. Thedisplay means does not include the screen 1 a and the translucent mirror3, and may be constructed by installing the image generator 2 at theposition of the screen 1 a in FIG. 2.

The infrared ray generating device 4 is a reference displaying devicefor generating references that are the bases for the detection ofcoordinates indicated by the player, that is, indicated coordinates,employs infrared laser, and is positioned on the inside, outer peripheryor back surface of the screen 1 a.

The references generated by the reference displaying means are displayedon the inside or periphery of the screen 1 a, and constitutebases forthe detection ofcoordinates as will be described later.

The reason for using the infrared ray generating device 4 for a devicefor generating references is to accurately and clearly detect thereferences by. displaying the references using infrared rays and passinglights through an infrared ray generating device 4 because the image ofthe game displayed on the screen 1 a is composed of electromagneticwaves of an invisible ray and, therefore, the references cannot bedistinguished from the image of the game, as described above.

Further, since in the present invention, coordinates are calculatedusing references arranged at intervals determined by a certain rule asdescribed later, unnecessarily detected points except for the referencescan be eliminated, thus further accurately detecting indicatedcoordinates.

The infrared generating unit 4 is positioned behind the translucentmirror 3, and the references are preferably arranged along a horizontalaxis of the screen 1 a passing through a center of the vertical axis ofthe screen 1 a. The infrared ray references generated from the infraredray generating device 4 passes through the translucent reflecting mirror3 and are displayed on the screen 1 a. In the case where the displaymeans is constructed by positioning the image generator 2 on theposition of the screen 1 a without using the screen 1 a and thetranslucent mirror 3, the infrared ray generating device 4 may bepositioned on the periphery of the screen 1 a or near the periphery ofthe screen 1 a.

The control means 5 is a means for controlling the entire shooting gamemachine by transmitting images, including a mark, to the image generator2 so that the player can see the images of the game, changing thecontents of the game depending upon the motion of the player anddetermining whether the mark is hit for the management of the game. Thecontrol means 5 can be implemented using a general microprocessor.

The model gun 10 is an indication means for pointing at a point of thescreen 1 a indicated by the player, and may be replaced by a tennisracket, a baseball bat, a baton, a rod, a sword, etc.

The model gun 10 includes a CCD camera 13, a lens 14, an infrared rayfilter 15, an image detecting means for detecting the image of a regionindicated by the indication means, and a trigger 11 for allowing theshooting of the player to be noticed. The CCD camera may be replaced bya Complementary Metal-Oxide Semiconductor (CMOS) element.

The infrared ray pass filter 15 functions to receive the images of thegame, including the mark displayed on the screen 1 a, eliminate thelight of a visual ray range, and pass the electromagnetic waves of aninfrared ray region therethrough.

The references composed of the electromagnetic waves of an infrared rayregion are formed on the CCD camera 13 by the lens 14, converted intoelectric signals, and transmitted to a coordinate detecting means 6 viaa communications line 16.

The coordinate detecting means 6 includes a reference coordinatedetecting means for detecting the coordinates of the references usingsignals detected by the image detecting means and transmitted via thecommunications line 16 and an indicated coordinate detecting means fordetecting indicated coordinates, which are indicated by the playerthrough the indication means, based upon the coordinates of thereferences detected by the reference coordinate detecting means. Thecoordinate detecting means 6 includes a means for converting analogsignals into digital signals when signals transmitted from the model gun10 are analog signals.

The coordinate detecting means 6 may always detect the indicatedcoordinates to change the contents of the game depending upon the motionof the player while the game is played, or may detect the indicatedcoordinates on at the moment the trigger 11 is pulled to reduce theburdens of the operations of the control means 5 or the coordinatedetecting means.

The indicated coordinates of a point, which is indicated by the player,detected by the indicated coordinate detecting means are transmitted tothe control means 5, and are compared with the position coordinates ofthe mark at the moment the player pulls the trigger 11 to determinewhether the player hits the mark.

The arrangement of the references is described as follows according tothe present invention.

In the prior art shooting game machine, one or two references areemployed. When three or more references are employed, they are usedwhile being arranged at regular intervals near the screen. In contrast,since the present invention employs the ratios of the distances ofreferences, at least three references are arranged at predeterminedintervals determined in consideration of the resolution of the screen 1a, the resolution, visible range (the range of the screen 1 a that canbe detected by the CCD camera at one time) and rotation limit (themaximum rotation angle that can be noticed when the player points at theimage) of the CCD camera, and the resolution of the gun, that is, therange in which the model gun 10 can detect the screen 1 a.

In the present invention, the process of accurately detectingcoordinates of the references may be divided into the step of findingthe actual information of the detected reference, that is, determiningwhich position the detected references occupies in the order ofreferences, and the step of detecting the indicated coordinates usingthe detected reference. In order to determine which position thedetected reference occupies in the order of the references, the CCDcamera 13 must always detect at least two distances, that is, at leastthree references. It is not necessary to detect all the references.Accordingly, the coordinates can be detected even using a CCD camera 13of low resolution.

In order to always detect at least three of the plurality of references,the intervals between the references are determined in consideration ofthe resolution of the CCD camera 13 (a CCD camera of high resolution maybe used when the interval between the references is great, and a CCDcamera of low resolution may be used when the interval between thereferences is short), the rotation limit of the CCD camera 13, theresolution of the gun, the resolution of the screen 1 a and the positionwhere the player is mainly situated during the game, and the referencedisplaying means is adjusted so that the plurality of references aredisplayed according to the determined intervals.

For example, the case where the rotation limit of the CCD camera 13 isrestricted to 30°, the entire screen 1 a can be detected within arotation range of 30°, but at least three references are not detected atthe same time in the end portion of the screen 1 a if the CCD camera 13is rotated at more than 30°. Also, the case where the standard positionis arranged randomly, if indication means is closer than standardposition, the image resolution capacity of CCD camera 13 becomes high.But if indication means is closer than any limit point, it is impossibleto measure the end position of the screen.

In contrast, if the position of the indication means is far from astandard position, the image resolution capacity of the CCD camera 13becomes low.

Since the size of the screen can be variously changed and the standardposition is proportional to the actual size of the screen 1 a, theintervals between the references are determined based on the resolution,visible range and rotation limit of the CCD camera and the resolution ofthe gun, and the constants for determining the size of the screen 1 aand the standard position are produced according to the determinedintervals. For example, if 150 cm is the standard position for thescreen 1 a of 73.66 cm (29 inch), 258 cm becomes the standard positionfor the screen 1 a of 127 cm (50 inch). By the above-described method,the various arrangements of the references can maintain the same effectfor the various sizes of the screen 1 a.

Further, as the difference between the intervals between the referencesbecomes greater, it becomes easier to distinguish the detectedreferences from other references.

Although the plurality of references may be displayed near theperiphery. of the screen 1 a by positioning the reference displayingmeans outside the periphery of the screen 1 a, the plurality ofreferences are preferably displayed on the inside of the screen 1 a bypositioning the reference displaying means behind the translucentreflection mirror 3, as illustrated in FIG. 2.

In the case where the plurality of references are arranged outside thescreen 1 a, the CCD camera 13 mounted on the model gun 10 to detect theimage of a region indicated by the player must be mounted on the modelgun 10 to be offset therefrom, as illustrated in FIG. 3 a, so that thedesign of the model gun 10 is limited. In the case where the pluralityof references are arranged on the inside of the screen 1 a, the CCDcamera 13 can be mounted on the model gun 10 to be aligned therewith, asillustrated in FIG. 3 b, so that limitations in the design of the modelgun 10 are eliminated.

The limitation in the arrangement of the references described above canbe correctly expressed by the following mathematical equation (as shownin FIG. 4 a, the case where the plurality of references are arrangedalong the horizontal axis of the screen 1 a passing through the centerof the vertical axis of the screen 1 a is taken as an example).

A peripheral marginal error ET, which is the minimum distance requiredso that at least three references exist within a certain distance fromthe periphery of the screen 1 a (or the periphery of a region in whichthe image is detected), and a general marginal error GT, which is aminimum distance required to detect at least three references when theinside region of the screen 1 a, exclusive of the periphery of thescreen 1 a (or the periphery of the region in which the image isdetected), is detected by the CCD camera, can be mathematicallycalculated.

If D₁(θ) and D₂(θ) are defined as${D_{1}(\theta)} = {\frac{S_{H} - {C_{H}\cos\quad\theta}}{2\tan\quad\theta} - {\frac{C_{H}\sin\quad\theta}{2}\quad{and}}}$${D_{2}(\theta)} = {\frac{\tan\quad{\theta\left( {{C_{w}\sin\quad\theta} - S_{H}} \right)}}{2} + \frac{C_{w}\cos\quad\theta}{2}}$in the case where the horizontal value of the resolution of the modelgun is S_(w) (not used because the references are indicated along thehorizontal axis), the vertical value of the resolution of the model gunis S_(H), the horizontal value of the resolution of the CCD camera isC_(w), the vertical value of the resolution of the CCD camera is C_(H),the rotation limit angle of the CCD camera is θ_(c) and the rotationangle of the CCD camera is θ (0≦θ≦θ_(c)), the minimums of the valuescalculated by the following equations become the values of ET and GT (iftwo or more conditions of the right side of ET(θ) are fulfilled at thesame time, results are calculated)${{ET}(\theta)} = \left( {{\begin{matrix}{{not} - {defined}} & \left( {{\left( \frac{S_{H}}{2} \right)^{2} + \left( {D_{2}(\theta)} \right)^{2}} \geq {\left( \frac{C_{H}}{2} \right)^{2} + \left( \frac{C_{w}}{2} \right)^{2}}} \right) \\{{not} - {defined}} & \left( {{D_{2}(\theta)} < 0} \right) \\{{D_{1}(\theta)}} & \left( \left. {{D_{1}(\theta)} < {{D_{2}(\theta)}}} \right) \right. \\{{D_{2}(\theta)}} & \left( {{{D_{1}(\theta)}} \geq {{D_{2}(\theta)}}} \right)\end{matrix}{{GT}(\theta)}} = \left( {\begin{matrix}{{not} - {defined}} & \left( {\left( \frac{S_{H}}{2} \right)^{2} + \left( {{D_{2}(\theta)}^{2} \geq {\left( \frac{C_{H}}{2} \right)^{2} + \left( \frac{C_{w}}{2} \right)^{2}}} \right)} \right. \\{{D_{2}(\theta)} - {D_{1}(\theta)}} & {otherwise}\end{matrix}.} \right.} \right.$

If ET(θ) and GT(θ) values are not calculated at θ(0≦θ≦θ_(c)) (notdefined), ET(θ) and GT(θ) do not exist.

The reference are arranged to allow the intervals between the referencesto be maximized within the range that fulfills the conditions of ET(θ)and GT(θ). For example, since ET and GT are 58.58 and 142.99,respectively, in the case where the limit angle is 15°, at least threereferences are arranged within a distance of 58.58 fromn the peripheryof the screen 1 a, and continuous three references are arranged within adistance of 142.99 to allow the intervals between the references to bemaximized.

A more accurate calculation of coordinates is possible by arranging thereferences based upon values mathematically calculated according to theresolution and visible range of the CCD camera 13, the resolution of themodel gun, the resolution of the screen 1 a and the standard position.

FIG. 8 a is a diagram showing the method of using the CCD cameraaccording to the prior art, and FIG. 8 b is a diagram showing the methodof using the CCD camera according to an embodiment of the presentinvention.

A practical, mass-produced and generally used CCD is fabricated in aratio of 4:3 to be consistent with the ratio of a horizontal side to avertical side of commercially used televisions and monitors (320×240,352×288, 400×300, and 640×480). CCDs having resolutions (360×240 and720×480), in which the number of the pixels on the longitudinal axis isgreater than that of the transverse axis, are used.

Citing a CCD having a resolution of 320×240 as an example, theresolution, which can best detect the image, of the model gun 10 used inthe prior art shooting game machine is 320×240 because the longitudinalaxis having more pixels is positioned along the horizontal direction, asillustrated in FIG. 8 a.

However, if the longitudinal axis having more pixels is positioned alongthe vertical direction according to the embodiment of the presentinvention, as illustrated in FIG. 8 b, that is, the CCD is used afterbeing rotated at 90°, the references are closely arranged along thehorizontal direction according to the certain rule, so that the imagedetection resolution 80 of the longitudinal axis has no problems.Accordingly, the resolution of the transverse axis positioned along thehorizontal direction is 427 (320×4/3) when a ratio of the general screen1 a of 4:3 is applied.

As a result, even though the prior art CCD is employed, the resolutioncan increase by (427×320)/(320×240)=136,640/76,800=178%, so that theimage detection resolution can increase by 178%.

Hereinafter, the operation of the embodiment of the present invention isdescribed based upon the above-described construction.

FIG. 6 is a flowchart of an entire system according to the embodiment ofthe present invention.

When the player points at the mark displayed on the screen 1 a whileholding the model gun 10 in this hands at step S00 and S01, thereferences are detected by the CCD camera 13 mounted on the model gun 10at step S02.

The references detected by the CCD camera 13 are transmitted to thecoordinate detecting means 6 via the communications line 16, and pointsdisturbing the references are eliminated by the coordinate detectingmeans 6 at step S03. The elimination of the points is made possible bydetermining whether each detected point is a reference in such a way asto compare the detected points with the information of the referencesbecause the information of the references is previously stored in theshooting game machine.

It is determined whether the number of points remaining after theelimination of the disturbing points is three or more at step S04. Thereason for this is that the detection of coordinates of the presentinvention is possible when the number of detected references is three ormore.

If the number of the remaining points is three or more, the indicatedcoordinates are calculated using a coordinate calculation algorithm thatwill be described later, and the distance between the screen 1 a and theplayer and the rotation angle of the model gun 10 are calculated at stepS05. If the number of the remaining points is less than three, theprocess returns to the initial step.

The indicated coordinates, the distance between the screen 1 a and theplayer and the rotation angle of the model gun 10 are transmitted to thecontrol means 5, and are reflected by the contents of the game includingthe images and the size of the mark.

Thereafter, it is determined whether the player has pulled the triggerat step S06. If the player has not pulled the trigger, the processreturns to the initial step. If the player has pulled the trigger, it isdetermined whether the mark is hit by comparing the indicatedcoordinates at that moment with the coordinates of the mark at step S07.Finally, it is determined whether the game is terminated, and if atermination signal is not detected, the process returns to the initialstep at step S08.

FIG. 7 is a flowchart of a coordinate calculation algorithm according toan embodiment of the present invention.

There is taken as an example of the case where the screen 1 a has theresolution that can be plotted in a range from 0 to 400 in a horizontaldirection, the CCD camera 13 has a resolution of 320×240 and is usedwith the side thereof having high resolution positioned along a verticaldirection (accordingly, the central coordinates of the CCD camera are(120, 160)) and the references are arranged at the positions of (19, 43,58, 141, 175, 200, 225, 259, 342, 357, 381).

The positions of the references are previously stored in the shootinggame machine, the intervals between neighboring references are (24, 15,83, 34, 25, 25, 34,.83, 15, 24), and the ratios of the intervalsneighboring references are (0.625000, 5.533333, 0.409638, 0.735294,1.000000, 1.360000, 2.441176, 0.180722, 1.60000).

The process of detecting coordinates by sensing the motion, in which theplayer points the model gun 10 at the screen 1 a or rotates the modelgun 10, starts only if the number of references input through the CCDcamera 13 is more than three at step S001.

If the number of previously input references is more than three, theintervals between the references are calculated at step S002.

When the distances between neighboring references are calculated, theratios between the intervals between neighboring references aresequentially calculated at step S003.

If the number of the input references is three after the ratios of theintervals between neighboring references are calculated, referenceshaving a ratio most appropriate to a given interval ratio at steps S003and S015. If in the above example, three references are input and theinterval ratio is 0.42, 0.409638 is a closest value and the detectedreferences are considered third, fourth and fifth references.

If the number of input references is four or more, references atpositions where the sums of the errors for the given ratios of theintervals are least are found at steps S003 and S025. If in thisexample, five references are input and the ratios of the intervals are0.74, 1.33 and 2.42 in the order of size, the detected, references arefourth, fifth, sixth and seventh references, since the least errors are0.735294, 1.360000 and 2.441176 when continuous references are extractedfrom the ratios of the intervals and compared with one another.

In this case, in the case where a seventh reference is not detected dueto the partial failure of the reference displaying means, fourth, fifthand sixth references are detected, so that the calculation ofcoordinates is possible.

The coordinates of the references are detected by the referencecoordinate detecting means based upon the references detected asdescribed above, and the indicated coordinates of a point indicated bythe player can be obtained by the following method at step S006.

The number of references used to calculate coordinates is two. Whenthree references are detected, left two references are used to calculatecoordinates. When four or more references are detected, it is preferableto calculate the indicated coordinates using two references, including areference that is closest to the center of the CCD camera 13 and areference beside the closest reference.

If the coordinates of two references (it is assumed that an left uppercorner is an origin) on the CCD camera 13, which are used for thecalculation, are p₁=(p_(1X), p_(1Y)) and p₂=(p_(2X), p_(2Y)), thecoordinates of the center of the CCD camera 13 are C=(C_(X), C_(Y)),predetermined values corresponding to the references are I₁ and I₂ inthe order of size, and e and d are defined as e=(p_(1Y)−p_(2Y, p)_(2X)−p_(1X)) and d=√{square root over((p_(2X)−p_(1X))²+(p_(2Y)−p_(1Y))²)}, respectively, the X coordinate andthe Y coordinate are calculated using$\left\lbrack {{\left( {{I1} + {\left( {{I2} - {I1}} \right)\frac{C\left( {p_{2} - p_{1}} \right)}{d}}} \right\rbrack\quad{{and}\quad\left\lbrack {\left( {{I2} - {I1}} \right)\frac{C^{*}e}{d}} \right\rbrack}},} \right.$respectively. In this case, the calculation equations of the X and Ycoordinates are obtained after it is assumed that a lamp is positionedat the center of a monitor. If the lamp is not positioned at the center,the calculation equations may be different.

If it is assumed that the origin of coordinates on the screen 1 a is theintersection between an extension line from the reference and the leftside of the screen 1 a, previously defined values I₁ and I₂ preferablyare the coordinates of the horizontal axis of the screen 1 a. Forexample, when the indicated coordinates are calculated using third andfourth references, the values of I₁and I₂ are 58 and 121, respectively.

After the indicated coordinates indicated by the player are calculated,the rotation angle of the indication means is obtained by calculatinghow much the indication means is inclined based upon the coordinates offound references and the previously input coordinates of references atstep S007. The rotation angle is calculated by the equationcos⁻¹((p_(2X)−p_(1X))/√{square root over (d)} (radian). If the sign of(p_(2X)−p_(1X))(p_(2X)−p_(1Y)) is positive, the positive sign means thatthe indication means has been rotated to the right. If the sign of(p_(2X)−p_(1X))(p_(2X)−p_(1Y)) is negative, the negative sign means thatthe indication means has been rotated to the left.

After the rotation angle of the indication means is calculated, thedistance between the found references on the CCD camera 13 and theactual distance between the references on the screen 1 a obtained by thepreviously input coordinates of references are measured at step S008.

When the distance between the screen 1 a and the indication means andthe distance between the found references on the CCD camera 13 are D andd, respectively, and the focal length of the lens 14 and the distancebetween references obtained based upon the previously input coordinatesof the references are f and L, respectively, the distance D between thescreen 1 a and the indication means is obtained by D≈f(L/d).

The process of changing the degree of difficulty and the situations ofthe game depending upon the distance D between the screen 1 a and theindication means is illustrated in FIG. 10.

Referring to FIG. 10, the player shoots the model gun 10 while pointingthe model gun 10 at the mark on the screen 1 a at step S100. At thistime, as the position of the model gun 10 is changed, the distance Dbetween the model gun and the screen 1 a is continuously measured in theshooting game machine at step S102.

The shooting game machine determines whether the measured distance D isappropriately maintained at step S103. That is, as shown in FIG. 9, thedistance between the screen 1 a and the indication means may be changeddepending upon the action of the player. Let the appropriate distance bedefined as a reference distance D₀. At this time, when the referencedistance D₀ is not a point but a distance having a certain variationrange, the variation range is set to D_(0a)˜D_(0b). If the distance D ismeasured and the measured distance D falls within the variation range, anormal state is maintained and a normal game is provided at step S104.If the measured distance D does not satisfies the variation range, thatis, the measured distance D is a shorter distance D₁ or greater distanceD₀, the degree of difficulty or the situations of the game are changedat step S105. That is, the game environment of a different condition isprovided depending upon a distance from the model gun 10, which inducesthe player to have an interest in the game.

Specified examples of changing the degree of difficulty of the game orthe situations of the game are disclosed in FIGS. 11 a to 11 e. FIGS. 11a to 11 e are flowcharts showing the various examples for changing thedegree of difficulty of the game or the situations of the game.

Referring to FIG. 11 a, if the distance D is less than the variationrange after evaluating the distance D at step S110 and the variationrange D_(0a)˜D_(0b), that is, the model gun 10 is positioned close tothe screen 1 a (for example, the model gun 10 is spaced from the screen1 a by the distance D₁), a bullet is made to deviate from the mark whenthe player pulls the trigger 11 at step S111. That is, the bullet doesnot hit the mark at which the player points and hits coordinates thatare offset from the mark in a certain direction. This induces the effectof reducing the possibility of hitting the mark when the player shootsthe model gun 10. In this case, another object other than the mark maybe hit. The equation of a specified example of this point is as follows.The view of this point is illustrated in FIGS. 12 a and 12 b. FIG. 12 ashows the trace of a bullet when only a pure error angle δ_(s) that themodel gun 10 has exists. FIG. 12 b shows an error angle δ_(s) when thepure error angle δ_(s) not only exists but also the shooting gamemachine causes a bullet to deviates. The equation exemplarily supportingthis point is disclosed as below. This equation is only an example togive an explanation, and may be freely modified.$\delta_{0} = \begin{bmatrix}\left( {\delta_{S} + {\tan^{- 1}\left( {k \times {{d_{S} - d}}} \right)}} \right. & \left( {d < d_{S}} \right) \\\delta_{S} & {otherwise}\end{bmatrix}$

δ_(s): error angle that model gun basically has

d_(s): critical distance between model gun and screen

k: constant determined depending upon model gun

In contrast, if the distance D is greater than any of the distances ofthe variation range, the action of increasing shooting accuracy is takenat step S112. That is, even though. the bullet hits a position away fromthe mark, the bullet may be considered to have hit the mark.

Referring to FIG. 11 b, if the distance D is less than any of thedistances of the variation range after evaluating the distance D and thevariation range D_(0a)˜D_(0b) at step S120, the size of the mark isreduced when the player pulls the trigger 11 at step S121. That is, thesame or tough conditions are provided regardless of the position of themodel gun 10 by adjusting the size of the mark depending upon thedistance from the model gun 10, which reduces the probability of hittingthe mark. An exemplary equation regarding this is disclosed below.$L^{\prime} = \left( \begin{matrix}{L \times k \times {{d_{s} - d}}} & \left( {d < d_{s}} \right) \\L & {otherwise}\end{matrix} \right.$

L′: reduced length

d_(s): critical distance between model gun and screen

k: constant set according to object

On the contrary, if the distance D is greater than any of the distancesof the variation range, the action of increasing shooting accuracy byincreasing the size of the mark at step S122.

Referring to FIG. 11 c, if the distance D is less than any of thedistances of the variation range after evaluating the distance D and thevariation range D_(0a)˜D_(0b) at step S130, a penalty is granted to theplayer when the player pulls the trigger 11 at step S131. The grantingof the penalty can be variously exemplified by preventing the playerfrom adapting himself to the game environment in such a way as toconsiderably reduce the moving speed of the player in the gameenvironment within a certain time, making continuous shootings difficultin such a way as to limit the height of a jump when the player jumps inthe game environment or to increase the intervals between shootings, orpreventing the player from easily following the mark in such a way as toincrease the moving speed of the mark. On the contrary, if the distanceD is greater than any of the distances of the variation range, a normalgame is provided to the player, as usual, at step S132, or an advantageis granted to the player.

RefelTing to FIG. 11 d, if the distance D is less than any of thedistances of the variation range after evaluating the distance D and thevariation range D_(0a)˜D_(0b) at step S140, the size of a picturedisplayed on the screen 1 a is reduced at step S141. This reduces thesize of the sight of the mark and, accordingly, the size of the mark isreduced. On the contrary, if the distance D is greater than any of thedistances of the variation range, the size of the mark is increased atstep S142. That is, as the distance is lengthened, the size of the markis enlarged in proportion to the lengthened distance, so that theability of the player is maintained. An example of the above-describedprocess is shown in FIGS. 13 a and 13 b. FIG. 13 a shows the size of thepicture displayed on the screen 1 a when the model gun 10 is positionedfar from the screen 1 a, and FIG. 13 b shows the size of the picturedisplayed on the screen 1 a when the model gun 10 is positioned close tothe screen 1 a.

Referring to FIG. 11 e, the distance D and the variations D_(0a)˜D_(0h)are evaluated at step S150. If the distance D is less than any of thedistances of the variations D_(0a)˜D_(0h), the situations of the gameare changed when the player pulls the trigger 11 at step S151. Thesituations of the game denote the set or background of the game, whichindirectly affects the game. In contrast, if the distance D is greaterthan any of the distances of the variations, the player is made toeasily point at the mark by clarifying the contour of the mark whilemaintaining the same set and background at step S152.

As described above, the present invention can accurately calculate thepoint on the screen 1 a at which the player points while holding theindication means, that is, the model gun 10. An accurate calculation ofthe indicated coordinates is possible even in the case where therotation of the model gun 10 is taken into account.

Further, the method of detecting the indicated coordinates can calculateindicated coordinates even when the CCD camera 13 detects part of thereferences. Accordingly, as shown in FIG. 4 b, the indicated coordinatescan be detected in a wide range even using the CCD camera 13 having aCCD of the same resolution. The indicated coordinates can be calculatedin the same range using the CCD camera of a low resolution.

Further, in the case where part of the reference displaying means failsand part of the references cannot be displayed, it is impossible for theprior art shooting game machine to calculate the indicated coordinates,as shown in FIG. 5 b. In the present invention, as shown in FIG. 5 b,although part of the infrared ray generating device 4 fails and part ofthe references are not displayed, the point indicated by the player,rotation and the distance between the screen 1 a and the indicationmeans can be calculated, thus increasing the duration of the shootinggame machine.

Further, the present invention can calculate the degree of rotation ofthe indication means and the distance between the screen 1 a and theindication means, and the control means 5 can adjust the degree ofdifficulty of the game and voluntarily change the images of the gamebased upon the calculated degree and distance.

That is, if the player approaches the screen 1 a, the player can easilyhit the mark, so that the control means 5 can increase the degree ofdifficulty by increasing the moving speed of the mark or reducing thesize of the mark. In contrast, if the player goes away from the screen 1a, the control means 5 can reduce the degree of difficulty by reducingthe moving speed of the mark or increasing the size of the mark.

Further, the prior shooting game machine manages the game regardless ofthe motion of the player, but the control means 5 of the presentinvention changes the images of the game while reflecting the rotationor movement of the indication means or the distance from the indicationmeans.

Accordingly, since the player can enjoy a game with the degree ofdifficulty and progress of the game changed in response to the motion ofthe player, the player can enjoy a more realistic shooting game.

The present invention is not limited to the above-described embodiments,and can allow various modifications and alterations performed by thoseskilled in the art. The various modifications and alterations fallwithin the scope and spirit of the invention defined by the accompanyingclaims.

INDUSTRIAL APPLICABILITY

As described above, the present invention causes the player to have agreat interest in the game by changing a game environment depending uponthe distance between the model gun and the screen.

The present invention increases interest in the game by changing theprogress of the game in such a way as to change the images of the gameor making the degree of difficulty different.

Further, the present invention provides the effect of enabling the fairmanagement of games because a game is made difficult if the actualdistance is shorter than the reference distance set between the modelgun and the screen and a benefit is granted to the player if the actualdistance is greater than the reference distance. For example, if theactual distance is shorter than the reference distance, the degree ofdifficulty is increased by a reduction in the size of the mark, theimposition of a penalty, an increase in the directional angle of abullet, etc. If the actual distance is greater than the referencedistance, a benefit may be granted to the player by increasing the sizeof the mark, providing an advantage, etc.

Accordingly, the player can enjoy the game with the degree of difficultyand progress of the game changed in response to the rotation of themodel gun manipulated by the player or the variation of the distance, sothat the present invention exhibits an effect of providing a realisticshooting game.

Further, since indicated coordinates can be calculated using only partof references by arranging a plurality of references according to acertain rule, indicated coordinates can not only be calculated in a widerange using a CCD camera of the same resolution but indicatedcoordinates can be also calculated in the same range using a CCD cameraof a low resolution.

1. A shooting game machine, comprising: display means for displayingimages, including a mark; reference displaying means for displaying aplurality of references that are arranged inside or around the displaymeans at irregular intervals and are bases for detection of coordinates;indication means for pointing at a point on the display mean, which isindicated by a player; image detecting means mounted on the indicationmeans to detect an image of a region indicated by the indication means;reference coordinate detecting means for receiving the detected imageand detecting coordinates of the references; indicated coordinatedetecting means for detecting indicated coordinates indicated by theindication means based upon the detected coordinates of the references;and control means for adjusting a degree of difficulty based upon adistance between the display means and the indication means, receivingthe detected indicated coordinates and controlling the entire shootinggame machine.
 2. The shooting game machine as set forth in claim 1,wherein the irregular intervals between the plurality of references aredetermined depending upon conditions of the shooting game machine, suchas a resolution of the display means, a resolution, a visible range anda rotation limit of the image detecting means, and the distance betweenthe display means and the indication means.
 3. The shooting game machineas set forth in claim 1, wherein the reference coordinate detectingmeans detects actual information of the detected references based uponratios of distances between the detected references if the imagedetecting means detects part of the references.
 4. The shooting gamemachine as set forth in claim 1 or 3, wherein the indicated coordinatedetecting means detects indicated coordinates based upon two of part ofthe references detected by the image detecting means.
 5. The shootinggame machine as set forth in claim 1, further comprising rotationdetecting means for detecting rotation of the indication means basedupon the plurality of references.
 6. The shooting game machine as setforth in claim 5, wherein the control means controls the imagesdisplayed on the display means based upon a variation of the indicatedcoordinates detected by the indicated coordinate detecting means or therotation detected by the rotation detecting means.
 7. The shooting gamemachine as set forth in claim 1, further comprising a distance measuringmeans for detecting the distance between the display means and theindication means based upon previously stored intervals between thereferences on the display means and intervals between the references onthe image detecting means, which are detected by the image detectingmeans.
 8. The shooting game machine as set forth in claim 7, wherein thecontrol means controls the images displayed on the display means basedupon a variation of the indicated coordinates detected by the indicatedcoordinate detecting means or the distance between the display means andthe indication means detected by the distance detecting means.
 9. Theshooting game machine as set forth in claim 1, wherein the control meanscontrols the images displayed on the display means based upon avariation of the coordinates detected by the indicated coordinatedetecting means.
 10. The shooting game machine as set forth in claim 1,wherein the indication means is a model of one of a gun, a tennisracket, a baseball bat, a baton, a rod or a sword.
 11. A shooting gamemethod, comprising the steps of: (a) displaying images, including amark, by a display means and displaying a plurality of references thatare bases for detection of coordinates; (b) detecting a partial image ofa certain region of a point indicated through an indication meansmanipulated by a player; (c) receiving the detected partial image,detecting coordinates of the references, and setting coordinates of thereferences to the detected coordinates of the references; (d) detectingindicated coordinates of the point indicated by the player based uponthe coordinates of the references; (e) measuring a distance D betweenthe display means and the indication means based upon previously storedintervals between the plurality of references and distances between thecoordinates of the references; and (f) setting reference distances D₀ tosome of distances D between the display means and the indication meansfalling within a certain range, and changing a degree of difficulty andsituations of the game depending upon whether the reference distancesare fulfilled.
 12. The shooting game method as set forth in claim 11,wherein the distance D between the display means and the indicationmeans is calculated by the following equationD≈f(L/d)where f denotes a focal length of a lens, L denotes a distancebetween the references obtained by previously stored coordinates of thereferences, and d denotes the intervals between the references on a CCDcamera; wherein the indication means is equipped at the front endthereof with the lens and at the rear end thereof with the CCD camera.13. The shooting game method as set forth in claim 11, wherein adirectional angle δ₀ of the indicating means is increased if thedistance D is shorter than the reference distance D₀, while thedirectional angle δ₀ of the indicating means is reduced if the distanceD is greater than the reference distance D₀.
 14. The shooting gamemethod as set forth in claim 11, wherein a size of the mark is reducedif the distance D is shorter than the reference distance D₀, while thesize of the mark is increased if the distance D is greater than thereference distance D₀.
 15. The shooting game method as set forth inclaim 11, wherein a penalty is granted to the player if the distance Dis shorter than the reference distance D₀, while an advantage is grantedto the player if the distance D is greater than the reference distanceD₀.
 16. The shooting game method as set forth in claim 15, wherein thepenalty is granted.to the player by a combination of a reduction in amoving speed of the player in the game, a limitation in a height ofjumps and a reduction ingame time.
 17. The shooting game method as setforth in claim 11, wherein situations of the game are set to bedisadvantageous to the player if the distance D is shorter than thereference distance D₀, while the situations of the game are set to beadvantageous to the player if the distance D is greater than thereference distance D₀.